What's the frequency? - Home Theater Forum and Systems - HomeTheaterShack.com

Old 07-04-10, 08:54 AM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
What's the frequency?

I have an awful peak at a certain low frequency - more about that in another thread - so I have decided to try to combat it using panel absorbers. I have built a couple - they are boxes, so I can move them around - but I have no idea how to confirm the resonant frequency and I haven't found a 'best practices for measuring membrane resonators'.

What I have tried:
I have bought an acoustic guitar pickup (is a piezo) which I attach to the membrane using powerstrips - I don't know its frequency response but I would assume that it is fairly flat (otherwise useless as a pickup).

I have put the speaker really close to the membrane near to the middle of the room - about 10cm's away and done a measurement 20-500Hz using REW.

I then took everything outside and did the same measurement in an attempt to remove the rooms influence on the measurement

The next measurement was done by simply thumping the membrane and using the rta in REW. Note the frequency scale is different to the previous two.

Which brings me to the title of the post: What is the frequency that the absorber resonates at, Kenneth?

The next question that arises is what effect would I expect to see on the rooms response?
Anyone else having fun measuring resonators?

Markus
MarkusBonk is offline

Old 07-04-10, 11:01 AM
Senior Shackster

Join Date: Feb 2009
Location: Australia
Posts: 171
Re: What's the frequency?

Room Dimensions ?
Mika75 is offline
Old 07-04-10, 12:05 PM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
Re: What's the frequency?

Quote:
Mika75 wrote: View Post
Room Dimensions ?
Well, outside is extremely large
Inside is a bit more difficult: its L shaped the | is about 5.56m * 3.88m * 2.44m, the _ is 4.88m * 2.43m * 2.44m (i.e bounding floor dimensions are 5.56m * 4.88m)

Markus
MarkusBonk is offline
Old 07-08-10, 12:06 PM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
Re: What's the frequency?

Am I correct in interpreting the responses such that everyone builds/buys some sort of resonator or equalizer and hopes for the best?
Quote:
Room dimensions?
What sort of post is that? - I am talking about measuring the resonant frequency of a panel resonator and some bot chucks
Quote:
Room dimensions?
at the thread. Probably it hasn't answered because its still trying to calculate the modes in the universe below 200Hz.

Oh, well...
MarkusBonk is offline
Old 07-09-10, 03:13 AM
Senior Shackster

Join Date: Feb 2009
Location: Australia
Posts: 171
Re: What's the frequency?

Quote:
MarkusBonk wrote: View Post
I have an awful peak at a certain low frequency - more about that in another thread - so I have decided to try to combat it using panel absorbers. I have built a couple - they are boxes, so I can move them around - but I have no idea how to confirm the resonant frequency and I haven't found a 'best practices for measuring membrane resonators'.
I didn't notice this initially, but I did see the thread u started about room modes so I thought u would get a better answer about it there ..
Mika75 is offline
Old 07-09-10, 09:56 AM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
Re: What's the frequency?

So I am right? If I want the usual voodoo - like chuck tons of absorbers at your room - then I am at the right place, if I want something scientific, void of all the hokus pokus I need to go somewhere else?
MarkusBonk is offline
Old 07-09-10, 11:46 AM
Senior Shackster

Join Date: Feb 2009
Location: Australia
Posts: 171
Re: What's the frequency?

Quote:
MarkusBonk wrote: View Post
I have an awful peak at a certain low frequency
If u only sit in a small area it would be possible to equalise it out.
Mika75 is offline
Old 07-11-10, 03:25 AM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
Re: What's the frequency?

Quote:
Mika75 wrote: View Post
If u only sit in a small area it would be possible to equalise it out.
Lets assume I am big and sit in a large area.
MarkusBonk is offline
Old 07-11-10, 03:53 AM

Join Date: Jul 2010
Location: Kongsberg, Norway
Posts: 14
Re: What's the frequency?

Hi.
What are the dimensions of the panel absorber you built?

Armand
Armand is offline
Old 07-11-10, 02:54 PM Thread Starter
Shackster

Join Date: Jun 2010
Location: Munich
Posts: 70
Re: What's the frequency?

The front panel is about 0.75 * 1.2m
MarkusBonk is offline

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